A unit of a phase is hereinafter represented by a radian. As a processing technology becomes elaborated and diversified, sophisticated measurement and analysis of, for example, a three-dimensional shape of an object is required, and various measurement methods have been developed. Among such measurement methods, an interference measurement technique using light interference, especially digital holography allows non-destructive and non-contact obtainment of three-dimensional information on an object. Therefore, digital holography is one of the measurement methods which have recently gained attention.
Digital holography is a technique for reconstructing, by use of a computer, an image of a three-dimensional object in accordance with an interference pattern (interference fringe) obtained by light irradiation to the three-dimensional object. Specifically, for example, an interference pattern formed by an object light beam obtained by light irradiation to a three-dimensional object and a reference light beam coherent to the object light beam is recorded by use of an image capturing device such as a CCD (charge coupled device). In accordance with the interference pattern thus recorded, an image of the three-dimensional object is reconstructed by calculating diffraction by use of a computer.
Inventors of the present invention have proposed a digital holography device which has a configuration such that a polarizer array is provided, e.g., attached to an image capturing surface of a CCD camera, the polarizer array splitting light emitted from a light source into two kinds of reference light beams having different phases in a plane perpendicular to a direction in which the light travels, and which has improved an image quality of a reconstructed image of a subject by a single shot (see Patent Literature 1).
Further, the inventors of the present invention have proposed a digital holography device which is capable of obtaining highly-accurate three-dimensional information in a deep range at a moment of a single shot by including: a polarized light splitting section which splits an object light beam into two kinds of object light beams that are polarized in different directions, so as to cause a difference in angle between directions in which the two kinds of object light beams are transmitted; and a polarizer array section in which a plurality of first polarizer regions and a plurality of second polarizer regions are provided and which transmits a reference light beam and an object light beam that reaches the polarizer array section via a subject (see Patent Literature 2).